OP Platinum GPS (the one with mag included) and DJI both use aux mag orientation = 0,0,0 if the arrow on the GPS is correctly pointing forward. Note that the arrow does not always match where the cable comes out of the GPS. For instance, authentic DJI GPS has arrow on same side as cable which seems backwards, but is actually a good thing if you think about it.
uBlox GPS with aux mag usually needs aux mag orientation = 180,0,180 = 0,180,0 if the arrow on the GPS is correctly pointing forward.
If arrow on GPS points some other way, you need to adjust orientation numbers (only the last number of the 3).